Renal dysfunction or failure and, in particular, end-stage renal disease, causes the body to lose the ability to remove water and minerals and excrete harmful metabolites, maintain acid-base balance and control electrolyte and mineral concentrations within physiological ranges. Toxic uremic waste metabolites, including urea, creatinine, and uric acid, accumulate in the body's tissues which can result in a person's death if the filtration function of the kidney is not replaced.
Dialysis is commonly used to replace kidney function by removing these waste toxins and excess water. In one type of dialysis treatment—hemodialysis—toxins are filtered from a patient's blood externally in a hemodialysis machine. Blood passes from the patient through a dialyzer separated by a semi-permeable membrane from a large volume of externally-supplied dialysis solution. The waste and toxins dialyze out of the blood through the semi-permeable membrane into the dialysis solution, which is then discarded.
Hemodialysis treatments are typically conducted at a clinic since the hemodialysis machines generally require a continuous water source, reverse osmosis machinery, and drain lines for discarding the large volumes of water and dialysis solution used during a single treatment. Hemodialysis treatment typically must be performed three or four times a week, under supervision of the clinical staff, requirements that significantly decrease a patient's autonomy and quality of life.
Certain devices reconstitute used dialysis solution from hemodialysis and/or peritoneal dialysis as opposed to discarding it. The dialysis solution can be regenerated in a machine employing a device that eliminates urea from the solution. For example, the original Redy® (REcirculating DYalysis) Sorbent System (Blumenkrantz et al., Artif Organs 3(3):230-236, 1978) includes a sorbent cartridge having five layers through which dialysis solution containing uremic waste metabolites flows in order to be regenerated.